DE1493741A1 - Process for the production of catechol mono-oxyalkylaethers - Google Patents

Description

14937A1

FARBWERKE HOECHST AG Gendorf, September 6, 1965

formerly Master Lucius & Brüning Dr.Br./Ws

description
to the

Patent application · "Process for the production of catechol mono-oxyalkyl ethers"

German Patent 352 983 describes the production of catechol monooxyethyl ether by reacting the mono-alkali metal salt of catechol with ethylene chlorohydrin or by adding ethylene oxide to catechol. According to Example 2, equimolecular amounts of catechol and equimolecular catechol are described. thylenoxyd heated of a catalyst in a closed vessel at HO to 15O ⁰ C without using from the aqueous solution of the reaction product -. a mixture of natural Auagangsmaterial, the monoethers and the diethers of catechol - the desired MonoätJier may be deposited crystalline by cooling with ice figures on. the yield of monoethers is not included in the patent.

..ird the oxyethylation of Brenzkateohin in the presence of conventional alkaline Oxalkylierungskatalysatoren, for example sodium hydroxide, carried out are likewise a mixture of the M receive three above-mentioned components, in which the mono-ether of catechol is present in amounts of $ 74.

Fun was proposed in German patent specification 874 445 at the etherification of pyrocateohin with dimethyl sulfate in benzene as Solvent and in a weakly alkaline medium (p ™ 8 to 9) too work, with the guaiacol (monomethyl ether) in 75-80 $ strength in addition to only $ 5-10 veratrol (dimethyl ether) is produced.

In my own attempts to transfer this teaching to the oxethylation of brentcatechol - i.e. in benzene and in the presence of a ■ weakly alkaline catalyst, for example sodium acetate However, no improvement over conventional oxyethylation can be achieved in the presence of sodium hydroxide,

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It has now been found that catechol mono-oxyalkyl ethers by exposure to equimolar amounts of molten catechol and low molecular weight alkylene oxides in the presence of iron or iron salts of inorganic and organic acids as catalysts Can produce in excellent yield and a high degree of purity, In principle, the same reaction can also be carried out in the solid state or in the presence of an inert solvent.

The selective addition of the alkylene oxides to one of the hydroxyl groups of the pyrocatechol takes place, according to the process, with a strongly positive exotherm. In two ways, by appropriately metering the inflow of alkylene oxide such as by cooling the batch, one has to ensure that a reaction temperature slightly above the melting point of pyrocateohin (melting point 104 ^° C.), for example in the range between 105 and 120 ^° C., is maintained, it can be advantageous to allow the oxyalkylation to proceed under nitrogen as a protective gas

The resulting process products can be removed from the fully reacted Separate the melt from the catalyst by distillation, wherein according to the degree of purity of the monoether one more or there is less advance of pyrocateohin.

Of the alkylene oxides to be used as starting materials according to the process, the main ones are ethylene oxide, propylene oxide and butylene oxide and called epichlorohydrin.

In addition to metallic iron (Ferrum reduotum), the iron salts of inorganic and organic acids, which are effective both in anhydrous form and as compounds containing water of crystallization, can be used as catalysts for carrying out the present oxyalkylation process. In particular, the chlorides and sulfates of ferrous and trivalent iron occupy a preferred position. The oxalkylation in the presence of catalytic amounts of Eisenphoephaten gives less satisfactory results. The amounts of catalyst to be used are generally between 0.05 and 5 wt. #, Based in each case on the starting compound, preferably between 0.5 and Xf>,

The content of the accruing melts obtained according to the method Monooxyalkylether can be immediately after completion of the reaction Determine by gas chromatographic analysis, in the case of implementation

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From BrenzkateGhin with ethylene oxide the mono ^ ß-oxyethyl ether is already obtained as a crude product (100 $ yield) with a degree of purity of more than 95 $ !!. The melting point can in this case used who «· the one who as close © at 99 to IQO ⁹ C lie _ö s should um for the purity of the product ent ** standenen | as good Kriter. Lower melting points indicate the presence of unreacted catechol and its dieter. In the case of reacting pyrocatephine with propylene oxide, the oxyalkylation leads to a liquid product with a particularly high monoether content of 99fo,

The method according to the invention can be carried out both in the laboratory m and on a technical scale. For larger operating? If quantities of alkylene oxide can be lost due to leaks in the boiler, the amount of oxide still missing for complete conversion can easily be determined on the basis of the melting point of the oxyalkylate. An overdose of alkylene oxide should be avoided as far as possible.

The invention relates to a process for the preparation of pyrocatechol mono ^ oxyalkyl ethers by the action of equimolecular crucibles of catechol and alkylene oxides, characterized in that the reaction is carried out in the presence of metallic iron or SdPaeai Salt ancup track more like organic acids than catalyst does.

Taking into account the fact that the selective oxalkylation of only one hydroxyl group of pyrocatechol with others than ca- * talysator known metal chlorides only in technically unsatisfactory Scale takes place and ^ - as based on our own investigations in a is shown in the table below - similar to gijte Aus * booty could not be achieved, it had to be regarded as surprising that the production of 4 mono-oxyalJlcylathfr des Pyrocatechins in excellent yield and a high degree of refinement it is possible »if © is close to this in accordance with the invention in the presence of Siaen or its salts as a catalyst egg? A formation of the products of the process in the Jinne of the Friedel-Crafts reaction can therefore not be accepted. In which unknown catalytic effect is apparently

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specific catalysis of iron and its jalze, presumably in Form of complex formation with catechol. flow surprising The selectivity of the mono-oxyalkylation, however, remains on such polyhydric phenols whose hydroxyl groups are bonded to adjacent carbon atoms. On resorcinol with two ' Meta hydroxyl groups, however, do not succeed with any catalyst the preferred preparation of the monoether with alkylene oxide.

The mono-oxyalkyl ethers of pyrocatechol produced by the process of the present invention are found as intermediates for the synthesis of pharmaceuticals and dyes, e.g. for the blueprint technique.

example 1

In a 250 ml 4-neck round-bottom flask equipped with a stirrer, contact thermometer, reflux condenser and grass inlet pipe, 110 g of pyrocatechol (1 mol) are weighed out together with 0.5 g of anhydrous iron (III) · ¹ · chlori'd and heated to HO ⁰ C melted together with stirring. In the thus obtained melt a reaction temperature of 105-110 ⁰ G are introduced 44 g A'thylenoxyd (lmole) in compliance. The reaction, which takes about 1 to 1 1/2 hours, is highly exothermic, so that the flask must be cooled. After cooling, the contents of the flask solidify to a solid crystal mass with a melting point of 95 ⁰ O. The gas chromatographic analysis of the crude. Reaction product gave the composition *

Pyrocatechol (unchanged starting material) ο, % pyrocatechol mono-ß-oxyethyl ether $ 97.7

Pyrocateohin-di-ß-oxyethyl ether $ 1.4

If, during further processing of the product, the contained therein Iron catalyst interferes, it can be separated from it by distillation of the product. In this way you get a right, a white Crystal! Sat, whose degree of purity depends on the respective performance depends on the fractionation column. l, J, with a short fractionation essay, filled with Raschig rings, a product with the following composition was obtained

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BAD OFIIGiNAL

Melting point 98 ⁰ C

Catechol

Pyrocatechol mono-ß-oxyethyl ether,, £ 5 $

Pyrocatechol-di-ß-hydroxyethyl ether !, If »

Example 2

In a V4A stirred tank with a capacity of 500 liters, which is equipped with the usual fittings for an oxyethylation vessel, 150 μg of pyrocatechol are melted under nitrogen as an inert gas. Then 0.75 kg of anhydrous iron-ClIIJ-chloride are added as a catalyst and about 1 ctd. long below. ^ j ter Jtickatoff stirred. Anachlieaaend 66 | $ lX hylenoxyd (= 60kg) in accordance with the consumption at 110 C under pressure zuflieasen gelasssen, wherein the boiler temperature should not exceed 12O ⁰ C. After the reaction has ended, the melt is filled into the provided packaging under nitrogen, in which it solidifies to a crystalline mass. The melting point of the product thus obtained was 88 G; The following composition was determined by gas chromatography:

Pyrocatechol '^' °

Pyrocatechol mono-ß-oxyethyl ether $ 91.5 Pyrocatechol di-ß-oxyethyl ether $ 2.2

For use as an intermediate product, e.g. for dye synthesis the product is separated from the catalyst by distillation and (| simultaneously fractionated. If necessary - by adding more ethylene oxide ("post-gasing") most of the still unchanged Pyrocatechol can also be converted into the oxyethylate.

Example 5

In a 250 ml 4-neck flask, as in Example 1, 220 g of pyrocatechol are melted with 1.0 g of anhydrous iron (III) chloride and reacted with 116 g of propylene oxide ^{at HO 0 G.} The product obtained is viscous and, according to the gaachromatographic analysis, is composed of t

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Catechol $ 0.4

Pyrocatechol mono-ß-oxypropyl ether JSSuWo

Pyrocatechol di-ß-oxypropyl ether $ 0.5

Example 4

In the same way, 110 g of pyrocatechol (1 mol) and 1 g of anhydrous iron chloride as a catalyst are reacted with 92.5 g of epichlorohydrin (1 mol). After 15 minutes, the exothermic reaction has ended and a product with the following composition t remains

Pyrocatechol 1 * 0 $

Brenzkat echin-mono-ß-oxy-y-chloropropyl ether 97.8 $

Fe pyrocatechol-di-ß-oxy-y-chloroethyl ether $ 1.2

The table below shows the implementation of catechol with ethylene oxide for the Pail. *. the results of the Descripti as Jtand art erwähn.Ien method as well as those ι recorded with the use of Friedel-Crafts catalysts without the iron salts and compared with the results according to the inventive process using iron or iron salts as catalyst

Catalyst consistency fo mono-

or Pp ⁰ C ether

without (according to DRP 352 983) salt porridge 65

^w NaOH (usual oxyalkylation) 78 74.5

Sodium acetate, anhydrous, in benzene

analogous to DBP 874 445 75 67.8

Friedel-Crafts catalysts and other added value. Non-ferrous metal salts

ZnCl ₂ »anhydrous viscous 38

• η 79 79

TicIi '"viscous 21

JnOIi »" "58

SbCl ₅ , "" 25

Orel ♦ "greasy 55.4

JJ-LjO ^ "after 2 hours of recording _"

4, from only 0.5MoI Αβο _ _Ä ^^

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■ S ... i ι «-

U93741

Catalyst consistency fa mono-

or PP ⁰ G äthor

: Eigen and iron eels

Perrum reductum (naoh. Pretreatment

with catechol) 93 95

Inorganic Elsenal Salts

PeSO., Anhydrous, drifted at 200OC »89 91 m

PeSO ₄ + H ₂ O 85-90. '

) ,, anhydrous 85 93

) ₅ + H ₂ O 80 02

PeCl ₂ , anhydrous 93 97

PeCl ₂ + H ₂ O 91 96

PeCl ,, anhydrous 95 98

Pe (NO ₃ ) ₂ 74 '78

Pe (NO ₃ ) ₃ 84 91.2

Organic iron salts

Iron (II) acetate 93 97

Iron (II) oxalate 90 95

Eiaen II lactate 78 91

Iron (II) citrate 84 92

Claims (4)

Patent claims 1. Process for the production of catechol mono-oxyalkyl ethers by the action of equimolar amounts of cateohin and alkylene oxides, characterized in that the Implementation in the presence of metallic iron or iron salts of inorganic and organic acids as a catalyst « 2. The method according to claim 1, characterized in that as Catalyst the chlorides or sulfates of the bivalent and trivalent ^ Iron used » 818/1084 ~ 8 * OBiQWAL * ' U93741 3. The method according to claim 1 and 2, characterized in that ala catalyst the salts of iron in anhydrous Shape used 4. The method of claim 1, 2 and 3, characterized in that the catalysts are referred to based on the output of · compound in amounts of 0.05 - 5 wt. ^, Preferably 0.5-1 GeW ₀ ^ applies.. 909818/1084